There often exists a requirement to secure an area against unauthorised personnel, particularly at night when they are able to move by stealth. Where the use of physical barriers or manned protection is impractical, other means of denying the area are required. One such possible method is to make unauthorised personnel feel uncomfortable and visible to others. This is termed a denial method.
One such method is the use of motion detection to activate lighting, which is commonplace in prior art. Such lighting is often used to deter intruders because it highlights their unauthorised presence to others, who might then challenge them or report them to security personnel. However the light is designed for illumination and not for disruption, and such methods turn on the light for typically many seconds or minutes, and therefore require a significant amount of energy, which cannot be supplied from small batteries. For this reason, and also because they are typically used outside, such systems should usually be wired to a mains supply, which requires skilled personnel to install. Such a system therefore cannot readily be deployed at short notice by unskilled personnel, or in areas where mains power is not available.
A further deficiency of this prior art is that each unit can only cover a small area, that which is within sensor range. Consequently, if a large area is to be covered, multiple units should be deployed, necessitating that each unit be small and lightweight.
It may also be required to deploy such devices covertly so that they cannot easily be found and disabled. This is another reason that they should be small.
Whilst it is possible to argue the definitions of “small” and “portable” in the context of this method, it can be seen that the limiting factor in making devices small and highly portable, is the energy required by a powerful light source that should be powered for at least several seconds, therefore requiring a battery or energy store of high storage capacity.
It is often necessary for a system to distinguish between authorised and non authorised personnel, so that authorised personnel may enter and leave the area at will without triggering the denial method. Such systems that exist in the prior art are “dumb”. That is to say, they simply turn on the light when any presence is detected, and do not distinguish between authorised and non-authorised personnel.
Background prior art is found in: Multi-action battery powered trigger activated lighting system US20090180280.